IGF1 and major depressive disorder: For feature selection, the demographic information, 24-item Hamilton Depression Scale (HAMD) score, Montgomery-Asberg Depression Rating Scale, Hamilton Anxiety Scale score, and neurotrophic factors (fibroblast growth factor-2 (FGF-2), nerve growth factor (NGF), insulin-like growth factor-1 (IGF-1), and VEGF) were used.